From: "Vladimir Galogaza" 
To: "ATM shore" 
Reply-To: "Vladimir Galogaza" 


Greg,

Although I am not an expert, here is my opinion.

>if proximity of the knife edge to the eye is troubling, why not
>eliminate the knife edge.  Use the edge of your pupil to cut the rays.

One reason is that longitudinal and sometimes transversal position of  the
KE has to be measured quite precisely in order to calculate figure of the
mirror under test. It will be difficult to do so with pupil edge.

In addition, pupil edge is positionaly very unstable due to combined motion
of our head and eye.

In practice it happens sometimes that shadow produced by pupils edge is
mistaken for one from actual KE.

Vladimir.

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